Textile Actuators Research Articles

Shape Memory Alloys in Textile Platform: Smart Textile-Composite Actuator and Its Application to Soft Grippers.

In recent years, many researchers have aimed to construct robotic soft grippers that can handle fragile or unusually shaped objects without causing damage. This study proposes a smart textile-composite actuator and its application to a soft robotic gripper. An active fiber and an inactive fiber are combined together using knitting techniques to manufacture a textile actuator. The active fiber is a shape memory alloy (SMA) that is wire-wrapped with conventional fibers, and the inactive fiber is a knitting yarn. A knitted textile structure is flexible, with an excellent structure retention ability and high compliance, which is suitable for developing soft grippers. A driving source of the actuator is the SMA wire, which deforms under heating due to the shape memory effect. Through experiments, the course-to-wale ratio, the number of bundling SMA wires, and the driving current value needed to achieve the maximum deformation of the actuator were investigated. Three actuators were stitched together to make up each finger of the gripper, and layer placement research was completed to find the fingers' suitable bending angle for object grasping. Finally, the gripping performance was evaluated through a test of grasping various object shapes, which demonstrated that the gripper could successfully lift flat/spherical/uniquely shaped objects.

Multimode opto-magnetic dual-responsive actuating fibers and fabrics programmed via direct ink writing.

Current methods lack one-step actuation programming for weave structures that can achieve multimodal motions in fiber and fabric actuators. Fiber and fabric actuators with dual-response to magnetic fields and near-infrared (NIR) light were fabricated via direct ink writing (DIW) in this work, and have 105.3 J kg-1 energy density, enabling multimodal motions including rolling, grasping, and transportation.

Relationship between friction of fabric on contact surface and recall sensation in tactile presentation using fabric actuator

Relationship between friction of fabric on contact surface and recall sensation in tactile presentation using fabric actuator

Micro-manipulation Interface that Presents Surface Force Tactile Sensation According to the Cell Deformation

The microinjection technique is widely applied in fields such as biology, medicine, and intracytoplasmic sperm injection (ICSI). Microinjection process requires special skill and, thus, generally ICSI is conducted by embryologists. However, the shortage of embryologists has become a problem in clinics, and there is a need for an easy injection system that does not rely on embryologists. In this study, we propose a micromanipulation interface that assists to perceive cell extension for easy injection system. The proposed interface provides 2-dimensional force/tactile feedback through a fabric actuator with air pressure based on real-time visual sensing of cell deformation. The effectiveness of the proposed interface is verified through puncturing experiments on perceiving cell extension perfumed by inexperienced subjects.

Effect of Segment Types on Characterization of Soft Sensing Textile Actuators for Soft Wearable Robots.

The use of textiles in soft robotics is gaining popularity because of the advantages textiles offer over other materials in terms of weight, conformability, and ease of manufacture. The purpose of this research is to examine the stitching process used to construct fabric-based pneumatic bending actuators as well as the effect of segment types on the actuators' properties when used in soft robotic glove applications. To impart bending motion to actuators, two techniques have been used: asymmetry between weave and weft knit fabric layers and mechanical anisotropy between these two textiles. The impacts of various segment types on the actuators' grip force and bending angle were investigated further. According to experiments, segmenting the actuator with a sewing technique increases the bending angle. It was discovered that actuators with high anisotropy differences in their fabric combinations have high gripping forces. Textile-based capacitive strain sensors are also added to selected segmented actuator types, which possess desirable properties such as increased grip force, increased bending angle, and reduced radial expansion. The sensors were used to demonstrate the controllability of a soft robotic glove using a closed-loop system. Finally, we demonstrated that actuators integrated into a soft wearable glove are capable of grasping a variety of items and performing various grasp types.

Analysis of driving forces of 3D knitted shape memory textile actuators using scale-up finite element method

The shape memory textile actuator uses a shape memory alloy that changes its crystal structure according to temperature and then returns to its initial shape, which is suitable for wearable applications that value wearing and portability. The shape memory effect of returning to the initial shape and the complex fabric structure influence each other, and accordingly, various drives have been measured in many studies. Therefore, in this study, the driving force, which is the most important physical property of the shape memory textile actuator, was analyzed through a scale-up finite element analysis. In the wire scale, a shape memory alloy wire was obtained for an analysis of the mechanical and thermal properties through tensile tests and DSC, and in the unit cell scale, a 3D knit structure was modeled using the Texgen and Weftknit programs. Finally, a supercell of size 5 × 5 was subjected to external deformation by displacement and heating conditions using disposition through the ANSYS program. The driving force was measured through microanalysis. Subsequently, the driving force of the manufactured shape memory textile actuator was compared and analyzed to determine the suitability of this method. Furthermore, the direction of subsequent studies was mapped based on the analysis presented on the differences in the maximum driving force and error rate.

Electrochemically Driven Yarn and Textile Actuators

Conjugated polymers such as polypyrrole can be electrochemically oxidised and reduced. These redox reactions are accompanied by a flow of counter ions and solvent from the electrolyte into or out of the polymer matrix in order to maintain charge balance and osmotic pressure, resulting in an electrochemically induced volume change of the conjugated polymer. This volume change can be exploited to fabricate electrochemically driven actuators in various formats from bending bilayer microactuators to macroscopic textile actuators. Yarn and textile actuators are fabricated by coating commercially yarns and fabrics with the conjugated polymers. First a thin layer of PEDOT (poly(3,4-ethylenedioxythiophene)) is applied to make the yarns or fabrics electrically conductive. Thereafter the yarns/fabrics are coated with electromechanically active polypyrrole using electrochemical synthesis. Next the yarn or textile actuators can be actuated by applying the appropriate redox potentials. In order to achieve in-air actuation, the yarns or fabrics will be coated with novel ionogels (gelled semi-solid electrolytes), that function as the ion source/sink to drive the electrochemical reactions. Two of such ionogel coated yarns will be assembled forming the anode/cathode pair of the electrochemical circuit. Using advanced textile manufacturing such yarn actuators can be integrated into fabrics using knitting or weaving. The latest results of our textile actuators both operating in liquid electrolytes as in-air will be presented.Fig. 1 A textile actuator with 4 inlay-knitted, in-air operating yarn actuators. Figure 1

Soft Robotic Fabric Actuator With Elastic Bands for High Force and Bending Performance in Hand Exoskeletons

In current designs soft robotic bending actuators, the need for high force capabilities is not adequately addressed. In this article, we present a new inflatable actuator that exploits textile manufacturing techniques, using an elastic band to improve both bend and force performance. At a pressure of 102 kPa, the index finger sized actuator exerts 24.8 N of force on the environment. It is also capable of a full 360 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> bending angle for pressures between 30 kPa and 102 kPa with a maximum bending stiffness of 288.4 N/m. We further demonstrate feasibility of this new actuator in a case study of an entirely fabric based soft robotic hand exoskeleton that increases robustness and user comfort. Our results suggest that textile robotics could provide an attractive solution in terms of the development of user-friendly hand exoskeletons.

Knot‐Architectured Fabric Actuators Based on Shape Memory Fibers

AbstractDue to recent progress on wearable robotics, developing high‐performance fabric and textile actuators to be integrated with various soft electronic devices is urgently needed and remains a challenging issue. Here, a novel knot‐architectured fabric actuator (KAFA), showing superior features such as self‐locking crossing, mechanical robustness, facile fabrication at very low cost, high force generation, and large actuation strain, is reported. The actuation principle of KAFA is based on the shape recovery of constituent nitinol fibers that can restore the memorized curvature in the knotted architectures. Further, the KAFA can be conveniently operated by Joule heating, resulting in reliable actuation due to its seamlessly conductive circuit network. In addition, the KAFA shows exceptionally high force, up to 1373 times its own weight and around 30% actuation strain. The newly developed fabric actuators are applied to a wearable actuation device to lift weighty luggage and an adaptive controllable surface to grip spiky, irregular, fragile, and slippery objects. These applications demonstrate the wide potential of KAFAs for future wearable robotic products such as rehabilitative devices and powered exoskeletons.

Assessment of Soft Actuators for Hand Exoskeletons: Pleated Textile Actuators and Fiber-Reinforced Silicone Actuators.

Soft robotic approaches have been trialed for rehabilitation or assistive hand exoskeletons using silicone or textile actuators because they have more tolerance for alignment with biological joints than rigid exoskeletons. Textile actuators have not been previously evaluated, and this study compares the mechanical properties of textile and silicone actuators used in hand exoskeletons. The physical dimensions, the air pressure required to achieve a full bending motion, and the forces generated at the tip of the actuator were measured and compared. The results showed that the construction method of the silicone actuators is slower than the textile actuators, but it generates better dimensional accuracy. However, the air pressure required for the actuators to generate a full bending motion is significantly lower for textile actuators, and the blocking force generated at that pressure is 35% higher in the textile actuators. There are significant differences across all variables compared, indicating that actuators constructed using pleated textile techniques have greater potential for the construction of an exoskeleton for hand rehabilitation or assistance.

Variable Shape and Stiffness Feedback System for VR Gloves Using SMA Textile Actuator

Currently, when direct human contact is limited owing to the coronavirus era, virtual reality systems are a technology that enables interaction without spatial restrictions. In this study, a system capable of feedbacking various shapes and stiffness when touching an object in virtual reality was conceived using the SMA textile actuator, which is a shape memory alloy (SMA) that remembers by training at 500 °C for 15 min with training tools that fixed shapes of SMA origin, and it returns to the shape at 40.13 °C or higher by Joule heating. SMA textile actuators were fabricated by zigzag stitching with 0.5 mm intervals. Various shapes were feedback because the SMA textile actuators on gloves interfere with the movement of the finger joints and the feedback force levels of stiffness are divided based on the number of actuators operating, and feedback is possible in three levels. We verified shape feedback that matches sensing points that are placed on the virtual finger joints created by Unity 3D, which is a software for making virtual reality to feedback points on VR gloves with three events using Unity 3D logs. We measured the forces of each feedback force level with SMA diameters 0.4 of 0.6 mm. The results showed 2.3 N with 0.6 mm; however, owing to its rigidity, 0.5 mm SMA textile actuator is appropriate. Finally, by implementing one feedback point of the VR gloves, we verified the operation of the system from the occurrence of an event by touching an object in virtual reality to control the feedback force level through the MCU and relay.

Wearable Sunlight-Triggered Bimorph Textile Actuators.

Photothermal bimorph actuators have attracted considerable attention in intelligent devices because of their cordless control and lightweight and easy preparation. However, current photothermal bimorph actuators are mostly based on films or papers driven by near-infrared sources, which are deficient in flexibility and adaptability, restricting their potential in wearable applications. Herein, a bimorph textile actuator that can be scalably fabricated with a traditional textile route and autonomously triggered by sunlight is reported. The active layer and passive layer of the bimorph are constructed by polypropylene tape and a MXene-modified polyamide filament. Because of the opposite thermal expansion and MXene-enhanced photothermal efficiency (>260%) of the bimorph, the textile actuator presents effective deformation (1.38 cm-1) under low sunlight power (100 mW/cm2). This work provides a new pathway for wearable sunlight-triggered actuators and finds attractive applications for smart textiles.

Pneumatic Textile Actuators for Transformable Spaces in the City of the Future

Today more than ever, urbanization is a global trend. More and more people around the world are living in cities, making cities very important problem solvers of tomorrow’s world. This addresses ever new questions about connectivity and mobility, but also about urban planning itself. One focus is the future design of buildings. Pneumatic textile actuators can positively influence the need for active tensioning of textile facade elements for the construction of the future. Initially, urban growth was strongly limited by the productivity of neighboring agriculture, as its surplus was the basis of supply [1]. However, this necessity was soon overcome, urban growth increased massively and in 2008, for the first time, more people lived in cities than in rural areas [2]. By 2030, the United Nations Population Federation projects 5.2 billion urbanites [3]. Cities have long since developed into conurbations, and there is increasing talk of redensification in their planning and organization. This refers to the use of vacant land in the area of existing developments and the increase in the volume of building space within existing developments.

Development and evaluation of pneumatic actuators for pediatric upper extremity rehabilitation devices

Textile pneumatic actuators were developed to provide full assistance to lift the arm of a model of an 11-year-old male beyond 120 degrees of shoulder abduction. Two fabrics and a variety of sealing techniques, methods of attachment, and actuator shapes were comparatively evaluated using textile and functional tests. The results identified that both fabrics and one of the three sealing techniques were effective for creating air-tight, functional actuators. Actuators were more effective when the bands attaching them were closer to the axilla. Rectangular and wing-shaped actuators, both lifting the model of an 11-year-old male’s arm above 120 degrees of abduction, were more effective than Y-shaped actuators. Multiple designs and materials may be acceptable for building textile pneumatic actuators to lift the full weight of a child’s arm. Compared to traditional hard robots, soft assistive robots offer key potential benefits related to comfort, aesthetics, weight, bulk, and cost.

Contractile Force and Stitch Modeling of Shape Memory Alloy Knitted Fabric Actuators

Contractile Force and Stitch Modeling of Shape Memory Alloy Knitted Fabric Actuators

Soft Robotics: Textile Technology for Soft Robotic and Autonomous Garments (Adv. Funct. Mater. 6/2021)

In article number 2008278, Vanessa Sanchez, Conor J. Walsh, and Robert J. Wood review the state of the art in textile-based wearable robots. The application areas for textile robots and their diverse needs drive materials innovations for textile actuators, sensors, and integration elements. Advances in materials and production technologies suggest a future of additively manufactured wearables where function is programmed at the fiber and fabric level.

Measurement of force exerted by fabric actuator with a 6-axis force/torque sensor

Measurement of force exerted by fabric actuator with a 6-axis force/torque sensor

Fabrication of Soft Textile Actuators Using NiTi Linear Shape Memory Alloy and Measurement of Dynamic Properties for a Smart Wearable

Fabrication of Soft Textile Actuators Using NiTi Linear Shape Memory Alloy and Measurement of Dynamic Properties for a Smart Wearable

A 2-DOF Shoulder Exosuit Driven by Modular, Pneumatic, Fabric Actuators

The shoulder plays a crucial role in moving the upper limb. It is capable of articulating in three degreesof-freedom, which enables the arm to perform kinematically complex manipulation actions. Wearable devices targeting the shoulder must be able to emulate its kinematics. Robotic exosuits are an attractive medium to provide shoulder assistance; but current soft robotic actuators feature limited mobility. This work presents a new 2-DOF soft robotic shoulder exosuit that utilizes modular soft actuators that are able to emulate the humerus' movement. The actuator design enables 3-D bending with insignificant resistance. Powered through separated inflation modules, these actuators are configured as two antagonistic pairs that operate in a parallel configuration. The actuator can reach full bending (>360°) with low pressures (~10kPA). The exosuit's actuators output 11.15N-m of torque at the neutral position, and 4.44 N-m at 90° shoulder elevation. A test performed on healthy subjects showed that use of the exosuit reduces muscle activation by up to 65% when performing shoulder elevation, and up to 34% when rotating the plane of elevation. The reduction in muscle activation highlights the promising ability of robotic exosuits in supporting arm movements through the entire range of their motion.

Flexible and Electroactive Textile Actuator Enabled by PEDOT:PSS/MOF-Derivative Electrode Ink.

Smart fabrics that integrate electronic devices with textiles are emerging as potential candidate for apparel and electronics industries. Soft actuators based on conducting polymers are promising for smart fabrics because of light weight, flexibility, and large deformation under low voltage. However, due to the distinct characteristics of textile and electronic components, the connection between textiles and electronic devices still keeps a challenge in development of smart fabrics. Here, we report an new strategy to prepare a flexible and electroactive textile actuator. The fabric electrolyte was directly coated with an electrode ink, which is composed of Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) doped with carbonized carbon nanotubes wired zeolite imidazolate framework-8 composite. A pre-treatment of the fabric was made by soaking hydrophobic poly(vinylidene fluoride-co-hexafluoropropylene) to increase the ionic conductivity (6.72 mS cm–1) and prevent the electrode ink from penetrating through the fabric. It was found that the textile actuator could work in air stably under a low voltage of 3 V and operate at frequencies from 0.1 to 10 Hz with large strain difference (0.28% at 0.1 Hz), fast strain rate (2.8% s–1 at 10 Hz) and good blocking force (0.62 mN at 0.1 Hz). The key to high performance originates from high ionic conductivity of fabric electrolyte and large specific surface area, good mechanical properties of the metal-organic framework derivative-based composite electrodes, which present insights into preparing other smart fabrics such as textiles sensors, flexible displays, and textile energy storage devices.